Many proposals have been made heretofore for workpiece clamping collets mountable in a lathe spindle and having provision for supporting workpiece stops of different sizes and configurations. Many of these include the provision for adjusting the support for the stop but all are subject to serious shortcomings and disadvantages owing to the inordinate amount of time and trouble involved in substituting one stop for another and adjusting the different stop to a precise position relative to the outer end face of the collet. It is common practice among many machinists to custom manufacture a stop for each job. The cost and time involved in constructing and installing the required stop renders it impractical in many instances to take a job if the required number of pieces for the job is relatively small.
Proposals have also been made heretofore to provide a spindle collet with a set of selectively usable stops. Disclosures of this type are to be found in Landreth U.S. Pat. No. 2,676,810 and Blanchard U.S. Pat. No. 3,720,416. Both of these proposals involve a complex assembly having a plurality of components required to be disassembled and reassembled each time a different stop is installed. Lacking in each of these prior proposals is any provision for assuring that, upon reassembly, the forward end of the new stop will be positioned properly until checking measurements have been made and various components are adjusted as necessary to achieve the required setting of the stop.